docs: def i_depend_on_them(decl):
          """Returns set of declarations. every item in the returned set,
          depends on a declaration from the input"""
  
          to_be_included = set()
          for dependency_info in get_dependencies_from_decl(decl):
              for ddecl in dependency_info.find_out_depend_on_it_declarations():
                  if ddecl:
                      to_be_included.add(ddecl)
  
          if isinstance(decl.parent, class_declaration.class_t):
              to_be_included.add(decl.parent)
          return to_be_included